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Measuring Diameter of a Laser Beam

IP.com Disclosure Number: IPCOM000083125D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Stafford, DW: AUTHOR

Abstract

This device, which may be hand-held, enables one to rapidly and accurately measure the diameter of a laser beam, and to investigate its intensity profile.

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Measuring Diameter of a Laser Beam

This device, which may be hand-held, enables one to rapidly and accurately measure the diameter of a laser beam, and to investigate its intensity profile.

A rotating first-surface mirror 10 is positioned to intercept laser beam 11. The mirror causes the reflected laser beam 12 to sweep slits 13 in stationary mask
14. Stationary photocell 15 generates an electrical signal in response to the time-displaced energy which passes through slits 13. This signal is stored in memory unit 16 for playback to oscilloscope 17 and/or X-Y recorder 18. The X-Y recorder may be used to provide an amplified trace of the beam's intensity profile for accurate scaling relative to an oscilloscope photograph.

The assembly 10, 14, 15 is mounted in accurate spatial relationship, on a base, not shown. The mirror 10 is rotated by synchronous motor 19 at a high speed, such that negligible error is introduced when the assembly 10, 14, 15 is hand-held.

The memory unit 16 is used to store a burst of data from the output of the photocell 15 as the beam traverses each slit 13 in mask 14. This memory-held data is then slowly read out to the X-Y recorder 18.

Two slits 13 are provided in mask 14 having known and accurate spacing. The width of the slits is known, and is wider than the expected laser beam diameter. From this, the laser's beam intensity profile and diameter can be readily determined.

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